This time, it's minicab drivers, who want TfL to suspend the recently launched UberPool ride-sharing service, claiming that by giving it the go ahead, TfL is "riding rough shod over the regulatory review process by pre-empting the consultation process... and ignoring rider concerns".
UberPool offers Londoners the ability to share a ride with someone nearby going in the same direction. It launched in November - just as TfL launched a consultation on proposals for new rules governing private hire vehicles in the capital, which would regulate both minicabs and Uber.
The group will hold a demonstration outside TfL's offices in Victoria between 12.15pm and 2pm today.
Responding to the group, a TfL spokesperson said that Uber's Pool service is not licensed separately, and does not need to be under current rules because it comes under its main operating licence.
The newly formed United Private Hire Drivers (UPHD) group behind the demonstration, is also calling for limits on the number of licensed drivers working in the capital.
"Private hire licensing in London is now out of control, with TfL handing out around 1,000 new licences every month. At more than 90,000 licenses there are 1.5 cars for hire for every street in the six-mile radius.
"Neither the market nor the street carrying capacity can sustain this. Driver incomes are plummeting far below poverty level and London’s streets are becoming too congested," said Terry Hoy, co-founder of UPHD.
Control over how many licences are issued is down to the mayor, TfL said.
The consultation on regulating Uber and other non-black taxis is due to close on 23 December. The outcome will decide the fate of Uber in the capital.